My IT dept is taking delivery of this machine in a couple weeks-
HP Z8 G4
2x Intel Xeon 6142 2.6 2666MHz 16C CPU
32GB (4x8GB) DDR4 2666 DIMM ECC Registered 2CPU Memory
HP Z8 G4 1125W PSU
so, similar, i intend to put it through its paces quite thoroughly when it gets powered up, and I'll post the results. Not an apples to apples compare, but might give an idea. Wasn't my choice of machines or setup, but they tagged it onto a rather large order they made for upgrading all the companies servers. So I'm thinking they got a good deal on it, and its from the local HP rep, so I couldn't push for a more economical brand or build.
Anyway, my only concern for you would be switching to laptops. I would hope that the specs for the laptops are quite high, I find that now that we have our network renderer up and running, the bottleneck for me is material and lighting development on my local machine. I would hope that doesn't slow down for you moving to a potentially slower laptop. I would love to have a faster machine for my cloudy plastics to resolve faster on so I can develop materials and lighting solutions faster on.